A specialist ship on its way to restore a vital communications cable linking Tonga to the rest of the world is expected to reach the archipelago this week, two weeks after a volcanic eruption and tsunami damaged homes, resorts, and infrastructure.

The ship left Port Moresby, Papua New Guinea, almost 5,000 km (3,000 miles) away on Jan. 20, according to Refinitiv Eikon data, and is expected to need a few weeks to carry out complicated repairs to the undersea cable.

“If the volcano blast or tsunami shifted or collapsed a seamount on top of the cable, it could be very difficult to locate or retrieve,” said Jonathan Brewer, a telecommunications engineer at consulting company Telco2 limited.

Faults in the world’s 436 active undersea cables are common and typically most traffic would be rerouted to another one nearby.

But Tonga’s 105,000 people are served by only one cable – to Fiji, some 800 km (500 miles) away – and their islands sit on the Pacific Ring of Fire, prone to earthquakes and volcanic eruptions. Communications were cut for five days after the latest eruption, and while some have been rerouted via satellite, they remain patchy.

The repair ship, CS Reliance, built by Tyco (now SubCom), is one is one of the largest vessels of its kind and can hold 5,466 metric tons of cable, enough to cross the Atlantic Ocean.

International rescue efforts are continuing following the eruption and tsunami, with drinking water, food and tents among the priorities.